The present invention relates to a field device search system designed to facilitate a search for one of a plurality of field devices (such as sensors and actuators) installed over a relatively wide area of a plant (factory).
In case a target field device that needs maintenance is searched for in a plant (factory) in a maintenance process, the target field device that needs maintenance has been accessed with the help of a drawing or memory of the worker in the related art.
FIG. 5 shows the concept of field device search in the related art. As shown in FIG. 5, a worker 3 is searching for a place where a field device 1 is located and a path thereto with the help of human memory while watching a drawing 2.
As techniques in the related art concerning a field device search system, the following patent references are known.
[Patent Reference 1] JP-A-2002-032166
[Patent Reference 2] JP-A-2004-021877
[Patent Reference 3] JP-A-2006-060696
Field devices include a sensor device such as a thermometer, a pressure measuring gauge or a flowmeter for measuring and detecting a physical quantity such as temperature, pressure or flow rate and transmitting the physical quantity to a controller installed in a position remote from the measurement site and an actuator such as a valve positioner or a switch for receiving a control signal transmitted from the controller.
The above field devices are widely used on plant sites of various types of industry sectors including petrochemical industry, foods and pharmaceuticals, water supplies and sewers, and steelmaking as well as utility control systems including air-conditioning, feedwater and drainage, power feeding and security in various types of buildings such as factories and constructions.
Communications of measurement data or control signals by such field devices have been generally made via cables in the related art. In recent years, such communications have been more often performed by way of wireless communication equipment.
In the procedure for setting such field devices, it is getting commonplace for a worker carrying a portable terminal equipped with the human-machine interface (HMI) to visit a site where a field device is installed and perform predetermined setting operation on a target field device through infrared or wireless communications by using the portable terminal.
In an attempt to search for a target field device in a plant, a worker used to access the target device to receive maintenance with the help of a drawing or human memory.
The related art has the problems described below.
Search for a device using a drawing or human memory is uncertain. In particular, in a plant (factory) where piping is arranged in a complicated way and field devices are widely installed, search for a device has to rely on w worker's memory while referring to a drawing.
For example, in a factory or a plant where wirelessly communicable devices are installed, search for a device may use the strength of radio waves. In this example, in case there is a gap in the service range of radio waves from a device, no information is obtained from the device. This makes it difficult to reach the device.